1. Field of the Invention
The invention relates to a method for the recording of an object space with an opto-electronic distance sensor by a signal propagation time method, with a transmitter for transmitting optical signals, in particular those of a laser, and a receiver device for receiving optical signals, in particular laser radiation, which is reflected from objects located in the target space. The distance sensor is combined with a scanning device for deflecting the optical axes of the transmitter and receiver device, and it has an evaluation device, which from the propagation time or phase angle of the optical signal emitted ascertains distance values. Downstream of the scanning device, that is, out of the region oriented toward the distance sensor, part of the beam is split off from the beam path of the transmitter and/or receiver device and is directed to receiver diodes or the like, and from the corresponding signals, a pixel is ascertained and each pixel is assigned a distance value and a space angle.
2. Background Information
Distance sensor scanners furnish so-called distance images, that is, images whose pixels, encoded in gray-scale value stages or false colors, indicate distance values. This technology has gained access to many areas of technology, such as architecture, building construction, etc. One advantage of these systems compared to conventional distance measuring devices is that in the shortest possible time, such a large number of points in the object space can be surveyed and documented that from these data, three-dimensional structures can be reconstructed. On the one hand, on the basis of a distance image of this kind, arbitrary other views of the three-dimensional structure can be generated, and on the other, these data can be further processed using CAD (Computer Aided Design) programs.
Such systems have found a particular application in the steel industry: Converters, ladles or the like in which steel melts are treated are exposed to relatively high wear. These converters or the like have a steel jacket which has an inner lining of kiln bricks. As a rule, this brick lining comprises at least two layers: an inner wear layer facing the melt, and a safety lining directly on the steel jacket. One essential task of this masonry lining is to protect the steel jacket against an excessive thermal load. Even a local defect in the masonry lining can lead to catastrophic damage to the system and must therefore be prevented with certainty. Besides, repairing or renewing the masonry lining is an extraordinarily complicated process and means a long down time.
To attain maximum operating safety on the one hand and on the other to assure the most economical possible operation of the system, the converters or the like are inspected. To that end, immediately after the evacuation of the converter, the container interior is surveyed with a distance sensor. Because of the brief measuring time and the tight network of measurement points, laser distance sensor scanners have proved themselves especially suitable for this task. Typically, after the masonry lining of the converter has been produced, the interior is surveyed, and several reference points are picked up on the converter itself that make it possible to represent the interior with reference to a fixed coordinate system. Upon an inspection during system operation, the interior is surveyed once again. The coordinate systems of both surveys are made to coincide, and the distance images are subtracted from one another. The resultant distance image then shows the deviations from the outset state of the masonry lining. Broken-away-bricks or extreme wear of the lining thus becomes visible.